The most numerous species on Earth are the insects. They outnumber humans by several hundred million to one.
For beetles alone, we’ve identified over 300,000 different species. Many beetles have a very versatile and effective defence system. Take for example, the bombardier beetle. Whenever the bombardier beetle is threatened by an enemy, it blasts its foe with a boiling hot mixture of stinging liquid and vapour. It fires this material out of a turret which can telescope and bend, allowing it to aim in any direction.
The bombardier beetle makes this explosive liquid by mixing together two hazardous chemicals, hydrogen peroxide and hydroquinone. In order to prevent themselves from becoming suicidal bombers who blow themselves up, they also add a stabilizing chemical known as an inhibitor. The lethal mixture is then stored in a reservoir located in the abdomen. When an enemy, say a frog, approaches, the bombardier beetle squirts the stored chemicals into two combustion tubes. At precisely the right moment, it adds an enzyme that neutralises the inhibitor, and it causes the chemicals to react explosively. The sequence of reactions is perfectly coordinated so that the explosion occurs right in the face of the attacker!
So next time you read about defence systems, think of beetles and marvel.